The Ka-band radars are particularly suited for cloud droplets and small rain drop regime measurements, by their capability to penetrate through rainand snow-falls and to detect small hydrometeors. Traditionally three moments of Doppler spectra are used as basis to retrieve microphysical cloud parameters, e. g. characteristic particle size (Gossard, 1997), liquid water content (Liao, 1994) and t...

In an urban environment, the occlusion of satellite broadcasts varies across space and thus, preplanning for collection of GPS points requires consideration of these obstructions. This paper presents a GIS embedded model (ArcGIS and ArcObjects) for predicting GPS error via modeling PDOP in an urban environment. The "skyview" model predicted PDOP for spatial locations as a function of the percen...

The recent availability of detailed geographic data permits terrain applications to process large areas at high resolution. However the required massive data processing presents significant challenges, demanding algorithms optimized for both data movement and computation. One such application is viewshed computation, that is, to determine all the points visible from a given point p. In this pap...

The calculation of viewsheds is a routine operation in GIS and is used in a wide range of applications. Many of these involve the siting of features, such as radio masts, which are part of a network and yet the selection of sites is normally done separately for each feature. The selection of a series of locations which collectively maximise the visual coverage of an area is a combinatorial prob...